This is a pilot study to develope reliable methods for the sampling and analysis of calcium, phosphate, hydrogen and fluoride ions in the same 5-10 nanoliter sample of dental plaque fluid obtained from plaque removed from individual surfaces of single teeth. The long-term objective is to use these methods to study the levels of saturation in plaque fluid at tooth sites which differ in susceptibility and current status (e.g. presence, severity) with respect to dental caries and to compare the kinetic changes in their composition after a sucrose challenge or other perturbations. The pilot study will investigate (a) methods of collecting dental plaque from single sites on individual teeth and of minimizing evaporative loss and salivary contamination during collections; (b) the effect of saliva:plaque ratios on plaque fluid composition, as a consequence of solute extraction from plaque bacteria or matrix and of possibly changing the equilibrium between free and bound calcium, phosphate, hydrogen and fluoride ions in dental plaque; (c) the effect of centrifugation on plaque fluid composition; (d) ion-selective microelectrode function and stability in 5-10 nl of plaque fluid and methods of avoiding or eliminating possible artifacts.